Biomedical subjects
Publications and source records attributed to J K Smith.
Pneumonia is a common disease seen in Emergency Department patients and is caused by a wide range of pathogens. The clinical and laboratory data that help to provide a specific etiologic diagnosis of the pneumonia are reviewed. In addition, current recommendations for the treatment and hospitalization of patients with pneumonia are detailed.
Methotrexate is used to treat a growing number of malignancies, severe rheumatoid arthritis, and refractory psoriatic arthritis. Pneumonitis induced by the drug occurs in a small percentage of patients and is usually associated with fever, cough, dyspnea, and restrictive pulmonary disease. Severe reactions may progress to respiratory failure. Early recognition of the toxicity is important, and discontinuation of the drug and therapy with corticosteroids usually lead to dramatic improvement.
We studied the incidence and prevalence of hospital-acquired infections in our intermediate-care units and the Nursing Home Care Unit at the Veterans Administration Medical Center, Johnson City, TN over a 4-year period (1980 through 1983). The global infection rate was 3.86 per 1,000 patient care days. The lower respiratory tract was the most common site of infection, followed by urinary tract infections, skin infections, bacteremia, wound infections, and infections at other sites. The prevalence study conducted by monthly visits over a 1-year period showed similar results. All of our patients were elderly males with multiple underlying diseases and poor performance status. The high incidence of nosocomial infections in chronic-care facilities relates to the poor functional assessment of the patients, which may increase the susceptibility of these patients to develop infections, mainly lower respiratory and cutaneous infections.
In the experiments described above, a neutralizing anti-ras antibody was utilized to study the role of ras protein in normal cell proliferation. Initially, it was demonstrated that the antibody was specific for ras protein, and that ras activity was efficiently inhibited. With the neutralizing antibody, it was first shown that ras activity is required for the proliferation of all normal cell types tested. ras activity was required just prior to initiation of S phase. The transforming activity of several retroviral oncogenes was also blocked following anti-ras injection. This included the tyrosine kinase, plasma-membrane-associated proteins, and an oncogene derived from a growth factor. On the other hand, cytoplasmic oncogenes with serine kinase activity were not dependent on ras activity for expression of the transformed phenotype. These observations form the basis of our model for proliferative signal transduction. We propose that the action of either growth factors, their receptor molecules, or related oncogenes initiate an intracellular signal received by ras proteins and then transferred by ras to cytoplasmic serine kinase oncogenes. This signal transduction system directly regulates cellular proliferation. Although further evidence in support of this model is needed, it appears from our studies that the mechanism of signaling between tyrosine kinases and ras proteins might be at the level of phospholipid metabolism. This observation is based on the fact that the mitogenic lipid molecules tested were remarkably dependent on ras activity, even more so than the growth factors or related oncogenes tested. Finally, our work suggests a fundamental distinction between normal and tumor cells. All the normal cell types tested were efficiently inhibited in proliferation by the injected antibody. Tumor cells, on the other hand, were never completely inhibited by the antibody and often were not inhibited at all. The presence of an activated ras oncogene within the tumor assured at least a partial role for ras activity in the proliferation of the mature tumor line. The significance of the observed distinction between normal and tumor cells is not known. The fact that this distinction involves a protein with an apparently critical role in normal proliferation suggests that the observation might be important.
Dysgonic fermenter 2 (DF-2) is a fastidious, gram-negative organism well recognized as a cause of fulminant septicemia in patients without spleens or patients with alcoholic cirrhosis. In vitro antibiotic susceptibility testing of eight strains with a Schaedler broth dilution technique revealed DF-2 to be susceptible to all of the antibiotics tested except aztreonam. Previous reports that DF-2 is aminoglycoside resistant were based on disk diffusion or agar dilution assays that may be less reliable given the slow growth of the organism and its requirement for CO2 incubation. Penicillin is commonly used as prophylaxis after dog bites and has excellent activity against DF-2.
The role of glucagon as a blood-borne mediator of the intestinal hyperemia associated with experimental diabetes mellitus was assessed in anesthetized fasted (18-24 h) rats 4 wk after the administration of streptozotocin (65 mg/kg body wt) or its vehicle. Selective removal of pancreatic glucagon from the circulation was accomplished by the intravenous administration of a highly specific glucagon antiserum. Blood flow to the gastrointestinal tract and kidneys was measured with radioactive microspheres using the reference sample technique. Blood flows were increased by at least 60% in each segment of the gastrointestinal tract of diabetic animals compared with control rats. Glucagon antiserum had no effect on blood flows in the gastrointestinal tract of control animals. However, the antiserum produced a significant reduction in blood flow to the stomach (26%), duodenum (25%), jejunum (12%), and kidneys (16%) in diabetic rats. There was no change in blood flow to the ileum or colon of diabetic animals with antiserum administration. The results of this study support the hypothesis that glucagon mediates a portion of the hyperemia noted in the stomach, duodenum, and jejunum. However, glucagon does not appear to play a role in the genesis of the hyperemia noted in more distal segments of the gastrointestinal tract (ileum and colon). A possible role for glucagon in the maintenance of renal blood flow in diabetic rats is suggested.
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A 39-year-old black male who is an intravenous drug abuser developed certain clinical manifestations that were consistent with the hyper-IgE syndrome. These included an extremely elevated IgE (greater than 2000 IU/mL), extensive eczematoid dermatitis, and recurrent soft tissue infections. He had no history of atopic disease as a child. Immunophenotypic analysis of peripheral blood mononuclear cells showed a significant decrease in helper (CD 4) cells with a normal concentration of suppressor (CD 8) cells. Human immunodeficiency virus (HIV) antibody was detected in his serum. Previous studies of patients with atopic dermatitis as well as of patients with the hyper-IgE syndrome characteristically show decreases in total suppressor lymphocyte concentrations in peripheral blood. These results led some investigators to postulate that high IgE concentrations in patients with atopic dermatitis result from defective IgE specific suppression. More recent evidence suggests that helper cell function may be the more critical impairment in these disorders. The development of a hyper-IgE syndrome in this setting of T-helper cell viral affliction lends further support to the hypothesis that helper lymphocyte defects may have a key role in the development of atopic dermatitis and the hyper-IgE syndrome.
Acetolactate synthase (ALS) is the first common enzyme in the biosynthetic pathways to valine, isoleucine, and leucine. It is the target of two structurally unrelated classes of herbicides, the sulfonylureas and the imidazolinones. Genomic clones encoding ALS have been isolated from the higher plants Arabidopsis thaliana and Nicotiana tabacum, using a yeast ALS gene as a heterologous hybridization probe. Clones were positively identified by the homology of their deduced amino acid sequences with those of yeast and bacterial ALS isozymes. The tobacco and Arabidopsis ALS genes have approximately 70% nucleotide homology, and encode mature proteins which are approximately 85% homologous. Little homology is seen between the amino acid sequences of the presumptive N-terminal chloroplast transit peptides. Both plant genes lack introns. The tobacco ALS gene was isolated from a line of tobacco which is resistant to the sulfonylurea herbicides due to an alteration in ALS. The tobacco gene which was isolated codes for an ALS that is sensitive to the herbicides, as assayed by transformation of the gene into sensitive tobacco cells.
This study examines the effects of heat treatment for 72 h at 80 degrees C on the potential thrombogenicity of lyophilized human coagulation factor IX concentrates. Since heating generated minor amounts of thrombin, concentrate was prepared with antithrombin III addition prior to heat treatment. Changes in coagulation parameters were followed prior to and after infusion of 100 iu/kg of heated and unheated concentrates to dogs. All batches produced a transient fall in platelet count during infusion and a delayed rise in plasma fibrinopeptide A, accompanied by a minor prolongation of the activated partial thromboplastin time. Such changes were less marked for heated batches. Control infusion of a 'failed' factor IX concentrate showed an additional fall in fibrinogen, rise in fibrin degradation products and a more rapid rise in fibrinopeptide A, while thrombin infusion caused an even more dramatic intravascular coagulation. These studies indicated no increase in the potential thrombogenicity of freeze dried factor IX concentrates as a result of heat treatment.
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Coagulation factor concentrates prepared in England are all subjected to heating in solution or in the lyophilised state. Concentrates of factor VIII, factor IX (II and X), factor VII and factor XI are terminally heated in the lyophilised state at 80 degrees C for 72 h but the current fibrinogen concentrate withstands only 70 degrees C for 24 h. 33 patients receiving factor VIII concentrate (code 8Y) and factor IX concentrate (code 9A) for the first time have had regular liver function tests (LFTs) and we have at least some data on 26 of them exposed for greater than 3 months. Of these 26 patients, four had received no blood products before 8Y, 15 had received only cryoprecipitate before 8Y, and seven had received no blood products before 9A. Nine have missed only one or none of their two-weekly tests, four have missed two or three tests and on the remaining 13, the LFT follow-up has been unsatisfactory, although in some cases clinical examination has been helpful. 12 batches of 8Y from greater than 70,000 donations and seven batches of 9A from greater than 40,000 donations have been used. In 13 patients who have had regular prospective LFTs, none has had an ALT or AST level above twice normal. One patient followed only irregularly has shown an isolated ALT rise at eight weeks, unconfirmed at nine or at 17 weeks.
Microvascular diameter and flow responses to peripheral and central sympathetic stimulation were measured in different segments of the arteriolar network in rat cremaster muscle. For peripheral stimulation, a bipolar electrode was placed on the internodal segment of the lumbar sympathetic chain between ganglia L1 and L2. For central stimulation, a bipolar electrode was stereotaxically implanted in the posterior hypothalamus. Inside vessel diameter, red blood cell velocity, and volumetric flow rate were recorded in response to electrical stimulations of varying magnitude in four series-coupled segments of the arteriolar network: 1A, 2A, 3A, and 4A. Systemic arterial pressure was also monitored. The vasoconstriction and flow reduction produced by stimulation of the lumbar chain was graded with the frequency of stimulation over the range of 0.5-16.0 Hz in all arteriolar segments. Examination of the relation between stimulation frequency and vasoconstrictor response measured as percent of control diameter indicated a sequence of responsiveness to peripheral stimulation where 4A = 3A greater than 2A = 1A. No changes in diameter were recorded in the venous microcirculation at any level of stimulation. Stimulation of the posterior hypothalamus with currents of 38-300 microA for 60 seconds produced graded vasoconstriction in only 3A and 4A vessels. Fluorescence histochemistry for biogenic amines was used to examine the distribution of innervation to the microvasculature. All segments of the arteriolar network from 1A to 4A possessed an adrenergic innervation; no vessels of the venous network were found to be innervated. The results indicate that the pattern of response of the arteriolar network in rat cremaster muscle to peripheral and central sympathetic stimulation is segmentally differentiated and consistent with the distribution of the vasomotor innervation.
A therapeutic concentrate of factor XIII containing both A and B sub-units has been prepared from 300 kg pools of human plasma. The process starts from a cold-ethanol fraction from cryoprecipitate supernatant and therefore does not interfere with the recovery of other clinically valuable plasma proteins. Factor XIII is purified approximately 600-fold from plasma by precipitation with sodium citrate and by the removal of fibrinogen by brief heating. The product has been pasteurised in sorbitol solution to inactivate blood-borne viruses, ultrafiltered to remove sorbitol, adsorbed with bentonite and freeze-dried in a formulation meeting requirements for intravenous injection.
Three patients who have been given intermediate purity NHS heat-treated factor VIII concentrate have been followed prospectively for 7-10 months. None had previously received more than six donor units of blood products containing factor VIII. There were no clinical side effects from concentrate administration, haemostasis was satisfactory and no patient developed clinical or laboratory evidence of hepatitis or HTLV III/LAV infection. Heat treatment resulted in the loss of slightly more than 20% of factor VIII activity but in vivo recovery of factor VIII and half disappearance times were within the expected range.
The facilitating effect of nifedipine on isoproterenol induced airway smooth muscle relaxation was studied in guinea pig tracheas. For isometric force measurement, 4 mm tracheal cylinders were suspended in incubation chambers in oxygenated physiologic medium. After 90 minutes of equilibration under 2 grams resting tension, at a temperature of 37 degrees C and pH of 7.4, concentration response curves for isoproterenol were performed with and without the addition of a 1 X 10(-5)M nifedipine dose. The experiments were then repeated using tissues precontracted with histamine. Our data show that in the nifedipine pretreated tissues, the EC50 of isoproterenol is shifted to the left (p less than 0.05) probably due to further reduction in cytosolic calcium by nifedipine. Our findings suggest that nifedipine might have a role in the treatment of asthma and obstructive airway disease.
An outbreak of four cases of type 8 Streptococcus pneumoniae pneumonia occurred on an Oncology Ward during a five-day period. All four patients had underlying malignancy and were in close proximity to each other on an open ward. No other patients or hospital personnel had type 8 S pneumoniae on throat or nasopharyngeal cultures. The implications of the outbreak with respect to transmission of this disease and role of pneumococcal vaccination are discussed.
A method for large-scale production of a pasteurized antithrombin III (AT III) concentrate for therapeutic use has been adapted from published methods. It includes the following steps: (1) batchwise adsorption onto heparin-Sepharose from plasma depleted of cryoprecipitate and prothrombin complex; (2) chromatographic elution at high salt concentration; (3) pasteurization for 10 h at 60 degrees C in the presence of added citrate ion; (4) desalting on Sephadex G-25, and (5) sterile filtration and freeze-drying. Seven batches prepared in this manner gave a mean yield of 269 U AT III/kg plasma. The product passed all the usual animal safety and pyrogenicity tests and has been used successfully in several courses of treatment of congenital deficiencies.